Hi Chandra
If the bus speed of the NE64 is 25MHz, the slowest clock which the SPI interface can generate is 12.21kHz and so is faster than the rate that you would like for your synchronous output. Running the NE64 at slower clock rates will not allow its Ethernet interface to work correctly.
It may be possible to use at timer interrupt to generate the clock timing and then 'bit-bang' the CLK and DATA lines at the speed which you require. This will involve an interrupt of around 100us period to produce a square wave on the clock line. If the external circuit can hanlde a pulse at the appropriate speed the interrupt could be reduced to half of the speed.
A further possibility would be to use the SPI in slave mode and drive its CLK input (output from the circuit) from a timer output. The timers can be programmed to generate an accurate frequency of 4800Hz (for example). By generating 8 pulses at the required frequency, an SPI byte can be clocked out of the SPI.
I am sorry but I don't have code to do these since it is a rather special solution but perhaps one of the methods will be appropriate for your needs.
Regards
Mark
www.uTasker.com
